The encapsulation of liquid substances and their controlled, targeted delivery is important to industry. However, the efficient encapsulation of liquid substances, especially volatile substances, has proven difficult. Although applications of encapsulation techniques are increasing year on year, there remain significant shortcomings and limitations. In particular, the encapsulation of volatile compounds is an area in which little progress has been made.
Particular problems are encountered in the encapsulation of perfume oils, which are volatile substances found in fine fragrances and other fragrance formulations. Although the use of microcapsules to encapsulate perfume oils has been proposed, fragrance formulations typically contain polar solvents such as ethanol in which the microcapsules are dispersed. These polar solvents can readily penetrate the wall of the microcapsules, causing the perfume oils to leach prematurely from the microcapsules. It would be desirable to provide microcapsules which enable perfume oils to be released in a controlled manner during use, e.g. by rupturing the microcapsules during normal human movement.
Various processes for microencapsulation are known. Unfortunately, many microcapsules manufactured have drawbacks that include, but are not limited to: (1) they cannot be formulated in certain classes of products due to strict formulation limits, (2) they are highly permeable when incorporated into certain products such as those that contain high levels of surfactant and solvents, resulting in the premature release of the active. (3) they can only effectively encapsulate a limited breadth of actives, and (4) they either are so stable that they do not release the active in use or have insufficient mechanical stability to withstand the processes required to incorporate them in and/or make a consumer product and (5) they do not adequately deposit on the situs that is being treated with consumer product that contains the microcapsules. Thus, there exists a need for microcapsules that can improve on at least one of these drawbacks.
There is a further need in the art for improved microcapsules for encapsulating liquid substances, especially microcapsules which exhibit an improved release profile. In particular, there is a need for microcapsules for encapsulating liquid substances such as perfume oils, wherein the microcapsules are substantially impermeable to polar solvents such as ethanol yet, at the same time, are capable of releasing their contents in a controlled manner during use. There is also a need for improved processes for the preparation of microcapsules.